Depression which interferes with maternal role functioning occurs in 10 to 15% of women following birth. This disorder causes personal and family suffering at a time when adaptation to the tasks of parenthood is critical. Women who have suffered devastating postpartum major depression fear repeating the experience after subsequent births, but there are no controlled studies regarding prevention of recurrent episodes. Specific Aims: A. The purpose of this study is to conduct a double-blind, randomized clinical trial of the efficacy of the antidepressant nortriptyline in the prevention of recurrent postpartum major depression. The preventive efficacy of nortriptyline will be compared to placebo during the first 20 weeks postpartum in 96 subjects. The hypotheses are: (1) the rate of occurrence of PPMD will be less in the nortriptyline-treated women compared to the placebo-treated women, and (2) of women who become depressed, the time to recurrence will be longer in the nortriptyline- treated women compared to the placebo-treated women. B. These mothers will be followed for the remaining 32 weeks of the first postpartum year. The goals for this naturalistic follow-up period are: (l) to evaluate the adequacy of the length of treatment (20 weeks) in the clinical trial, and (2) to determine if the rate of and time to recurrence after the clinical trial differs among women who took nortriptyline compared to women who took placebo. C. To identify prospectively the clinical predictors of recurrence during the clinical trial.